Cryogenic Cooling Schemes for the SPL U. Wagner TE-CRG

Topics  Introducing remarks  General considerations  Basic parameters  Basic considerations  Different cooling schemes (seven in total)  Cooling scheme options  Advantages / Drawbacks  Topics to be investigated 6/11/20092SPL Workshop NOv. 2009

Introduction  The SPL is presently in the phase of a Design Study.  CERN has no experience operating pulsed SC cavities at 2.0K.  We try to define a “baseline” design for the cryogenic distribution.  However this design will look like, we cannot consider this as “the Solution”; it may still be subject changes.  None of the proposals in this presentation is considered to represent the desired baseline. 6/11/2009SPL Workshop NOv General note

Introduction  Availability is a key requirement for all accelerators  The SPL is “second-in-line” of an injector chain  Availability even more important  Operation should be considered under degraded conditions like: Leaks Faulty components High local heat loads 6/11/2009SPL Workshop NOv Availability

Basic parameters  The following is considered as decided:  Cooling of the cavities with helium II at ~ 2.0 K  Cavities inside the saturated bath  To profit from low  p and good p-stability  (Not cooled by sub-cooled pressurized helium)  Anything else may be discussed / changed 6/11/2009SPL Workshop NOv Assumptions that are considered as decided

Basic parameters 6/11/2009SPL Workshop NOv Capacities The choice of the cryogenic distribution may influence the static heat load only !

Basic parameters LineTemperaturePressureDesign Pressure Header A2.2 K0.3 MPa2.5 MPa Header B2.0 K3.1 kPa0.6 MPa Header C5.0 K0.55 MPa2.5 MPa Header D8.0 K0.50 MPa2.5 MPa Header E50 K1.8 MPa2.5 MPa Header F75 K1.7 MPa2.5 MPa 6/11/2009SPL Workshop NOv Pressures and temperatures These values are fixed The rest is for “orientation” only and may be modified

Basic Considerations  The distribution scheme needs to satisfy requirements for:  Nominal operation  Cool-down, warm-up and purge  Operation under degraded conditions  Diagnosis  Safety equipment 6/11/2009SPL Workshop NOv Distribution scheme requirements Considered Not yet considered To be defined / discussed

Basic Schemes 6/11/2009SPL Workshop NOv Single Cavity Cooling LP SPLHP SPL Diameter “x” [mm]4080 Thermal shield and coupler cooling in “series” He II cooling Coupler cooling Thermal shield cooling Cool-down / Warm-up Purge

Basic Schemes 6/11/2009SPL Workshop NOv Single Cavity Cooling LP SPLHP SPL Diameter “x” [mm]4080 Thermal shield and coupler cooling in “parallel” He II cooling Coupler cooling Thermal shield cooling Cool-down / Warm-up Purge

Basic Schemes  Advantages  Less equipment  Simple operation  Disadvantages  No isolation of single elements in degraded conditions  “Last-in-line” always on higher limit temperature  Long response time for control  Advantages  Isolation of single elements possible  Little temperature spread  Short response for control  Disadvantages  More equipment  More control effort 6/11/2009SPL Workshop NOv “series” versus “parallel” cooling Series coolingParallel Cooling List not necessarily exhaustive

Module Schemes 6/11/2009 SPL Workshop NOv Scheme no 1: “Single cavity cooling” LP SPLHP SPL Diameter “x” [mm] %

Module Schemes  Simply a combination of single cavity cooling loops  Liquid HeII: individual per cavity  Coupler: in series or parallel for several cavities  Thermal shield:in series or parallel for several cavities  WU / CD:individual per cavity  Equipment intensive  Feasibility seems guaranteed 6/11/2009SPL Workshop NOv Comments on scheme no 1

Module Schemes 6/11/2009 SPL Workshop NOv Scheme no 2: “Common bath cooling” LP SPLHP SPL Low  High  Low  High  Diameter “x” [mm] %

Module Schemes  Combination of several cavities in one bath  Liquid HeII: one loop per bath  Coupler: in series or parallel for one or several baths  Thermal shield:in series or parallel for one or several baths  WU / CD: one loop per bath  Low amount of equipment needed  Feasibility seems possible  Cooling by conduction in the bath requires very big channel diameters  Could be feasible for LP version with 3 / 4 cavities per bath 6/11/2009SPL Workshop NOv Comments on scheme no 2

Module Schemes 6/11/2009 SPL Workshop NOv Scheme no 3: “ILC-like” LP SPLHP SPL Diameter “x” [mm] %

Module Schemes  One cavity per bath with common 2-phase header  Liquid HeII: one loop per group of cavities  Coupler: in series or grouped for several cavities  Thermal shield:in series or grouped for several cavities  WU / CD: one loop per group of cavities  Low amount of equipment needed  Feasibility of the WU/ CD questionable  The combination of several 2-phase volumes seems dangerous  The equal distribution of flow for CD (less for WU) seems difficult to guarantee  He II loop should be thermo-hydraulically validated 6/11/2009SPL Workshop NOv Comments on scheme no 3

Module Schemes 6/11/2009 SPL Workshop NOv Scheme no 4 : “ILC-like SPL version A” LP SPLHP SPL Diameter “x” [mm] %

Module Schemes  One cavity per bath with common 2-phase header  Liquid HeII: one loop per group of cavities  Coupler: in series or grouped for several cavities  Thermal shield:in series or grouped for several cavities  WU / CD:one loop per cavity  High amount of WU/ CD valves  Feasibility seems ok  He II loop should be thermo-hydraulically validated 6/11/2009SPL Workshop NOv Comments on scheme no 4

Module Schemes 6/11/2009 SPL Workshop NOv Scheme no 5 : “ILC-like SPL version B” LP SPLHP SPL Diameter “x” [mm] %

Module Schemes  One cavity per bath with common 2-phase header  Liquid He II: as ILC-like SPL version “A”  Coupler: as ILC-like SPL version “A”  Thermal shield:as ILC-like SPL version “A”  WU / CD:one loop per group  Low amount of equipment  Feasibility of WU /CD with contact cooled liquid helium tank to be investigated  He II loop should be thermo-hydraulically validated 6/11/2009SPL Workshop NOv Comments on scheme no 5

Module Schemes 6/11/2009 SPL Workshop NOv Scheme no 6 : “ILC like SPL version “A” with separate cryogenic feeder line” LP SPLHP SPL Diameter “x” [mm] %

Module Schemes  One cavity per bath with common 2-phase header  Liquid He II: as ILC-like SPL version “A” (or “B”)  Coupler: “parallel” cooling  Thermal shield:“parallel” cooling  WU / CD: as ILC-like SPL version “A” (or “B”)  High amount of equipment  Feasibility as for ILC-like SPL version “A” (or “B”)  All cooling loops of a group of cavities can be completely isolated  Independent WU/CD not possible 6/11/2009SPL Workshop NOv Comments on scheme no 6

Module Schemes 6/11/2009 SPL Workshop NOv Scheme no 7 : “ILC like SPL version “A” with separate cryogenic line equipped for independent cool-down, warm-up and purge” 1.7 %

Module Schemes  One cavity per bath with common 2-phase header  Liquid He II: as ILC-like SPL version “A” (or “B”)  Coupler: “parallel” cooling  Thermal shield:“parallel” cooling  WU / CD: as ILC-like SPL version “A” (or “B”)  Very high amount of equipment  Feasibility as for ILC-like SPL version “A” (or “B”)  All cooling loops of a group of cavities can be completely isolated  Independent WU/CD and purge possible 6/11/2009SPL Workshop NOv Comments on scheme no 7

Separate cryogenic line  Advantages  Less complexity for the main cryostat  Potential to completely isolate “faulty” modules  Disadvantages  Requires more tunnel space  Higher static heat load  Cost aspect  Not easy to identify separate line most probably more expensive  More complex cryostat and installation vs. cryostat plus line, two installations and more tunnel space 6/11/2009SPL Workshop NOv Advantages / Disadvantages

Single Module WU / CD Option 1: WU of complete machine -> exchange / repair -> CD complete machine  All machine warm –Possible with schemes 1 to 7 Option 2: WU distribution headers & concerned loops -> exchange / repair-> CD distribution headers & concerned loops  No active cooling for rest of machine –Possible with scheme 1 to 7 but increased radiation load for schemes 1 to 5 -> preferable scheme 6 & 7 Option 3: WU individual module -> exchange / repair -> CD individual module  Active cooling for rest of the machine –Possible only with scheme 7 6/11/2009SPL Workshop NOv Procedure options for exchanges / repairs

Open Topics  Ambient-temperature equipment  What can be at ambient, what must be at ambient?  Magnets cooling  If possible at ambient, why operate lower?  Coupler cooling  5-8 K best compromise? (why not 4.5 K – 300 K e.g.)  WU / CD  Contact cooled WU/CD of helium tank feasible? (would save on equipment) 6/11/2009SPL Workshop NOv To be investigated 1

Open Topics  Limits of operation under degraded conditions  When is a repair / exchange mandatory  Cool-down and warm-up times for the whole machine  “Natural” warm-up by static heat load for  Modules without active cooling (scheme 6)  Modules without active cooling and warm headers in cryostat (scheme 1 to 5)  Time necessary for exchange / repair of faulty components 6/11/2009SPL Workshop NOv To be investigated 2

Last Slide Thank you for your attention 6/11/2009SPL Workshop NOv